1. Field of the Invention
The present invention relates to a tuning apparatus, and more specifically, to a tuning apparatus for a printhead capable of linearly adjusting the displacement of the printhead via an inclined plane.
2. Description of the Prior Art
Printers at the present time are equipped with growing specific functions, design diversity, delicate process of manufacturing, and technology applied. With critical requirement for output quality, printers are made and assembled with exquisite components in which include the most substantial quality-related component, the printhead. Unfortunately, the printhead must face a challenge about its position displacement when assembled into the printer. The position displacement of a printhead is usually caused by manufacturing error of the printhead, assembly error of the components or component wearing during a period of time of operation. Many printers according to the prior art has tuning apparatus for its printer accordingly and the correction of the position displacement of the printhead is carried out before the first use of the printer or during the operation of the printer once the problem exists.
Please refer to FIG. 1. FIG. 1 is an illustration of a tuning apparatus 1 for a printhead according to the prior art. The tuning apparatus 1 comprises a carrier 10, an exertion component 20, and an eccentric cylinder 30. The exertion component 20 is fixed on the carrier 10 where a printhead (not shown in the figure) is located. The eccentric cylinder 30 has its eccentric hole rotatably configured on the carrier 10 and the eccentric cylinder 30 itself extending to a rectangular hole 21 of the exertion component 20, tangent to the left and right sides of the rectangular hole 21 and forming gaps between the top and bottom sides of the rectangular hole 21. The eccentric cylinder 30 pushes the exertion component 20 when rotating and therefore causes the carrier 10 to slightly move along the direction N1 or direction N2 for tuning the location of the printhead.
Please refer to FIG. 2 and FIG. 3. FIG. 2 is an illustration of every primary parameter of the eccentric cylinder 30 and FIG. 3 is an illustration of the relation between the rotation degree α of the eccentric cylinder 30 and the displacement t of the printhead, where R is the radius of the eccentric cylinder's outer circle, d is the eccentric distance of the eccentric cylinder's inner circle, and α is the rotation degree of the eccentric cylinder 30. The displacement t of the printhead caused by the rotation degree α of the eccentric cylinder 30 can be expressed by the following equation:t=|√{square root over (R2+d2−2Rd cos α)}−(R−d)|;
The above equation tells that the tuning apparatus 1 in the prior art possesses a nonlinear relation between the displacement t of the printhead and the rotation degree α of the eccentric cylinder 30, which is also shown in FIG. 3. As a result, the correction amount for the displacement of the printhead cannot be precisely tuned by rotating the eccentric cylinder 30. While in other practice of the prior art, the rotation degree of the eccentric cylinder 30 is calculated and inscribed thereon for adjusting the displacement of the printhead, and the nonlinear characteristic of the structure still leads to unsatisfactory accuracy.